Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. As a result, over the years, well architecture has become more sophisticated where appropriate in order to help enhance access to underground hydrocarbon reserves. For example, as opposed to vertical wells of limited depth, it is not uncommon to find hydrocarbon wells exceeding 30,000 feet in depth. This may be particularly true in cases of offshore operations, where depth as measured from the platform is increased by the distance to the well head at the ocean floor.
In recognition of the potentially enormous expense of completing sophisticated wells such as those offshore, added emphasis has been placed on well monitoring and maintenance. That is, placing added emphasis on increasing the life and productivity of a given well may help ensure that the well provides a healthy return on the investment involved in its completion. Thus, over the years, well diagnostics and treatment have become more sophisticated and desirable facets of managing well operations.
The nature of offshore wells presents unique challenges in terms of well access and management. For example, during the life of a well, a variety of well access applications may be performed within the well with a host of different tools or measurement devices. Providing downhole access to such wells may necessitate more than simply dropping a wireline into the well with the applicable tool located at the end thereof. For example, in circumstances where a clean-out application is to be run or a deviated well section is present, coiled tubing is generally employed to provide access to wells of more sophisticated architecture.
A coiled tubing application provides a hydraulic line for use in a wellbore and is also particularly adept at providing access to deviated or tortuous well sections. During a coiled tubing operation, a spool of pipe (i.e., a coiled tubing) with a downhole tool at the end thereof is slowly straightened and forcibly pushed into the well. This may be achieved by running coiled tubing from the spool at the offshore platform, through a gooseneck guide arm and injector which are aligned over the conduit to the subsea well head. Thus, where a deviated well section is present, forces needed to drive the coiled tubing therethrough are available.
Well diagnostic tools and treatment tools may be advanced and delivered via coiled tubing as described above. Diagnostic tools, often referred to as logging tools, may be employed to analyze the condition of the well and its surroundings. Such logging tools may come in handy for building an overall profile of the well in terms of formation characteristics, well fluid and flow information, etc. In the case of production logging, such a profile may be particularly beneficial in the face of an unintended or undesired event. For example, unintended loss of production may occur over time due to the buildup of debris or other factors. In such circumstances, a logging tool may be employed to determine an overall production profile of the well.
With an overall production profile available, the contribution of various well segments may be understood. Thus, as described below, corrective maintenance in the form of a treatment application may be performed at an underperforming well segment based on the results of the described logging application. For example, in the case of debris buildup as noted above, a clean-out application may subsequently be employed at the location of the underperforming segment.
In recent years, fiber optics capacity has been added to coiled tubing. In this manner, downhole data such as that making up the noted production profile, may be acquired in real-time. That is, an accurate production profile may be obtained via coiled tubing without removing the entire coiled tubing for profile data to be interpreted in advance of running a treatment application.
Unfortunately, while coiled tubing with fiber optic capacity may be time saving once deployed, it may also be time intensive in assembly, particularly offshore. That is, as with any coiled tubing, its offshore assembly and use is guided by conditions that are particular to the offshore environment. For example, for any particular piece of equipment, its weight is generally limited to about 50 tons so as not to exceed the capacity of the crane at the offshore platform. However, in the case of say, a 2⅞ inch coiled tubing for deployment in a 20,000 foot well, its overall weight may easily exceed 70 tons. Therefore, the coiled tubing is generally cut into separate segments for separate ship to platform deliveries so as to make sure that the crane capacity is not exceeded.
In addition to the separate deliveries of separate coiled tubing segments, subsequent reassembly or re-coupling of the segments to one another is needed. However, a considerable amount of time is lost in equipping the assembled coiled tubing with a fiber optic line. That is, the assembled bare coiled tubing is equipped with fiber optics by pumping of the line through the tubing. This involves the rigging up, and later breaking down, of pressure generating equipment, waiting hours for the proper pressure bulkhead to be generated, and waiting several hours for the line to be pumped through the tubing. For the example scenario of a 20,000 foot well as noted above, it may take between about 7 and 12 hours for the pumping of the line alone.
In addition to the time lost waiting for the fiber optic to be pumped through the tubing, there are concerns over the line traversing the joints between the separate tubing segments. That is, connector mechanisms which are used in coupling separate coiled tubing segments to one another present a sudden reduced tubing inner diameter. Thus, in order to effectively equip the tubing with communicative capacity the advancing line should bypass such connector mechanisms without suffering communicative damage thereto. Offshore operators are ultimately left with the options of continuing to run separate logging and coiled tubing operations or running a single trip coiled tubing application that faces the risk of line damage and eats up a considerable amount time over the course of its assembly.